Stereographic photography, or the taking of two pictures of an object from different positions so as to create a three-dimensional image thereof, is well known. At least as early as World War II, the principles and apparatus thereof were commonly used to survey enemy positions and strengths. The human eyes, along with the image merging capabilities of the brain, serve as another well known example of the process. A commonly available toy, the "Viewmaster", offers a simple, but effective, demonstration of the the efficacy and development of this art. Not as well known, but still within the purview of one skilled in the art, is the fact that two such photographs may be conjointly analysed so as to actually measure the third dimension which recedes from or approaches the cameras. Stereographic projectors are often used in such endeavors.
This depth measuring capability has, heretofore, not been utilized to its fullest extent. For example, the exact distance of an of one end of an object, with respect to a set of stereo cameras, can be accurately determined. The exact distance from the other end of those objects can also be accurately determined by a second set of stereo cameras. If, in addition, the exact distance between the two sets of stereo cameras is known, and the objects have a predictable variation in cross section along their length, the exact lengths and volumes of the objects can be easily determined.
Log scaling, or the measurement of the length, diameters, and therefore, volume of logs, has not changed for over 50 years. Typically, logs are purchased by volume and transported to the millsite where each load of logs is scaled to determine the incoming volume. This process is currently performed by one or more persons (scalers) who physically and manually measure each log on the load. Scalers must measure all critical dimensions of every log in order to determine accurately the volume of lumber in that log. It should be mentioned that this does not simply mean measuring a single length and diameter of each log and then computing its volume based on the assumption that it is a right circular cylinder. Rather, logs are often thicker at one end than the other, thus requiring a diameter measurement at each end. For this reason, at least two scalers are usually employed. Additionally, the ends of a log may not be a true circular cross-section but may be elliptical or oval. The butt ends of the log may not be perpendicular to its longitudinal axis. Scalers are also required to judge the quality of the logs as to type, texture, density, grain, and other aspects. All these elements combine to require that a scaler be a highly skilled workman possessing expertise in estimation and experience in judgement. It comes as no surprise that scalers often command a high rate of pay. Nevertheless, the accuracy and reproducibility of manual scaling remains poor because of the inherent difficulty of the job.
Scaling is normally done while the logs are on the transport vehicle. Many times manual scaling is done at both the pickup and the delivery site. For example, the logs may be scaled by the U.S. Forest Service to determine the amount of lumber taken from the forest and scaled again at the millsite to determine the amount entering the mill. Therefore, an expensive delivery vehicle and its crew can be idle for over an hour per load. The magnitude of the problem becomes clear when it is realized that a hundred thousand dollar truck cannot achieve the delivery productivity for which it was designed because of this enforced idleness.
Under the current state of the art, only a handwritten or hand entered tally of the scale information is preserved. This tends to impugn the integrity of any later verification or audit of the contents of any given load. If a mistake is made on a tally sheet the error is not capable of being rectified at a later date. This can become a source of dispute between users, suppliers, and carriers of the logs.
It can be seen that present systems of measurement, in particular the system of log scaling, suffer from many disadvantages. My invention, particularly applicable to log scaling, but not limited thereto, overcomes all the previously mentioned disadvantages as well as providing significantly greater accuracy and reproducibility than any known system.